1. Field of the Invention
The present invention relates to a visual indicator for an aerosol medication delivery apparatus and system used for administering a dosage of a substance in aerosol form to a patient.
2. Discussion of Related Art
The use of an aerosol medication delivery apparatus and system to administer medication in aerosol form to a patient's lungs by inhalation (hereinafter “aerosol delivery system(s)”) is well known in the art. As used herein: the term “substance” includes, but is not limited to, any substance that has a therapeutic benefit, including, without limitation, any medication; the term “patient” includes humans and animals; and the term “aerosol delivery system(s)” includes pressurized metered-dose inhalers (pMDIs), pMDI add-on devices, such as holding chambers, devices including a chamber housing and integrated actuator suited for a pMDI canister, nebulizers and dry powder inhalers. Examples of such aerosol delivery systems are disclosed in U.S. Pat. Nos. 4,627,432, 5,582,162, 5,740,793, 5,816,240, 6,026,807, 6,039,042, 6,116,239, 6,293,279, 6,345,617, and 6,435,177, the entire contents of each of which are incorporated herein by reference. Conventional pMDIs typically have two components: 1) a canister component in which the medication particles and a propellant are stored under pressure in a suspension or solution form and 2) a receptacle component used to hold and actuate the canister and having a mouthpiece portion. The canister component typically includes a valved outlet from which the contents of the canister can be discharged. A substance is dispensed from the pMDI by applying a force on the canister component to push it into the receptacle component thereby opening the valved outlet and causing the medication particles to be conveyed from the valved outlet through the receptacle component and discharged from an outlet of the receptacle component. Upon discharge from the canister, the substance particles are “atomized” to form an aerosol.
In the case of pMDI holding chambers, the holding chambers typically include a chamber housing with a front end and a rear end. The mouthpiece portion of the pMDI receptacle is received in an elastomeric backpiece located at the rear end of the chamber housing. An example of such a backpiece is disclosed in U.S. Pat. No. 5,848,588, the entire contents of which are incorporated herein by reference. The front end of the chamber housing includes an inhalation valve or a containment baffle or both and an interface, such as an adapter, a mouthpiece and/or a mask. The interface can be coupled to the front end of the chamber housing or integrally molded to the front end of the chamber housing. Some holding chambers include an integrated receptacle for a pMDI canister thereby eliminating the need for a backpiece or other equivalent structure used to receive and hold the mouthpiece portion of a pMDI.
One problem that currently exists with many aerosol delivery systems is that there is a lack of a visual indication to alert a caregiver when a patient is inhaling. In the case of a pMDI used in conjunction with a holding chamber, for example, it is important for a caregiver to know if the patient is inhaling at a rate sufficient to open the inhalation valve to allow the aerosolized medication to exit the holding chamber. It is also important to know when the patient is inhaling in order to coordinate the actuation of the pMDI with inhalation.
The present invention proposes to overcome the above-described problem, and other problems as described further below, by using a visual indicator in an aerosol delivery system. Such a visual indicator is particularly helpful with patients who do not have established breathing patterns. These patients, such as infants and small children, generally have very low tidal volumes.
Some known holding chambers on the market maintain that it is possible to determine breathing patterns by looking through the chamber for the movement of the inhalation valve. This is difficult to do in the case of low tidal volumes when the valve will only move a minor amount. If the chamber has an accumulation of drug deposited on the walls then this further impedes the viewing. Several examples of such devices are discussed below. First, U.S. Pat. No. 5,385,140 discloses a holding chamber that has a crosscut valve with four petals that lift during inhalation. At lower tidal volumes the petals will lift a small amount, but this can be difficult to see since there are numerous supporting ribs directly in the line of sight. A second device is disclosed in U.S. Pat. No. 6,039,042 where a clear adapter is used to view breathing patterns by way of the valve. However, the inhalation portion of the valve that moves is directly in the drug pathway and has only slight movement at lower flow rates (approximately 20°). Note that the entire contents of U.S. Pat. Nos. 5,385,140 and 6,039,042 are incorporated herein by reference.
With some of the other devices on the market it is possible to view the exhalation portion of the breath, but this is not considered to be as important as seeing the inhalation portion. One such device is disclosed in U.S. Pat. No. 6,293,279, the entire contents of which are incorporated herein by reference. The device has a mask with an exhalation valve that moves during exhalation, but at the lower tidal volumes this movement is not obvious.
Another problem that occasionally occurs, when the interface includes a mask, is a poor seal between the patient's face and the mask. Such a poor seal may adversely affect the delivery of aerosolized medication to the patient. The use of the above-mentioned visual indicator would be helpful in alerting the caregiver to verify whether there is a poor seal between the patient's face and the mask and, if so, to readjust the mask on the patient's face to improve the seal.